Graphene transparent conductive heating layer on the glass optical elements were examined. The inhomogeneity of the graphene resistivity and defects like scratches or holes may affect temperature distribution of all over the heated surface. Infrared imaging of Joule heated sample indicates significant uniformity deterioration in the presence of mechanical defects. Modelling of the Joule heating distribution in the graphene layer was performed using finite element method. The modelling results were compared with experimental infrared imaging results of Joule heated graphene samples and a good agreement was found. The infrared imaging gives an effective and nondestructive method for examining of uniformity of graphene transparent electrodes.